Field of the Invention
The present invention relates generally to a water purification system and more specifically to a system and method for monitoring and cleaning a water pre-treatment system including backwash and regeneration of all media tanks used to provide water to a primary purification system.
Description of the Related Art
Dialysis systems for treatment of patients with kidney disorders are in widespread use throughout the health care industry. These systems all require a constant source of purified water that removes organic and inorganic substances and microbial contaminants from the water to be supplied to a plurality of hemodialysis stations at which patients are treated. Most dialysis water systems employ a plurality of pre-treatment components for removing these contaminants. For example, a plurality of filtration tanks such as multi-media filters, granular activated carbon filters (GAC's), granular activated carbon polishers, and water softeners are arranged in series to supply dechlorinated water to a primary purification system for dialysis use.
These prior art systems require frequent, periodic cleaning to ensure that contaminants filtered through the process do not build up in the filtration tanks over time. Typically, these tanks must be backwashed, whereby clean water is forced in a reverse flow direction through the media tanks and then out into a drain system to remove contaminants that build up in the filtration media. The backwashing process is, in many cases, accomplished manually through operation or actuation of control valves that reverse fluid flow through the filtration tanks. In some prior art systems, the backwash process for each individual filtration tank is accomplished by utilizing a timer-actuated control valve that provides for the flow of water in a supply or filtration direction during a “normal” operating mode, and switches the water flow to a “backwash” mode or cycle of operation at a set time period during each day or week depending upon the timer settings for that control valve.
However, these timer-activated systems suffer from a great number of disadvantages. Initially, unless an operator is actually present at the time the backwash mode of operation is occurring, there is no way to know that the appropriate backwash operation occurred. Additionally, since most dialysis water systems employ multiple filtration tanks such as multi-media filters, granular activated carbon filters, and water softeners, these tanks must be backwashed individually rather than simultaneously since the flow of water required for a backwash or rinse cycle is quite high, and most water supply systems can't accommodate multiple tanks backwashing simultaneously since a reduced water flow rate would not provide sufficient backwash or rinse flow. System cleaning typically occurs late at night when the dialysis stations are not in use. When timer-actuated backwash operation is used, if an operator times more than one filtration tank to backwash in the same time period, the water flow rates to each tank may be insufficient to provide proper contaminant reductions.
Further compounding this problem is that when backwash operations occur late at night, an operator may not be present to determine that an incorrect backwash operation has occurred, i.e., that two or more tanks have backwashed simultaneously. In this situation dialysis water system operation may be suboptimal or indeed hazardous to patients since the filtration tanks are not sufficiently cleaned to remove contaminants from the water.
Additionally, in many prior art dialysis systems the contaminant level in the water must be monitored by taking frequent samples and testing them manually to verify that the water is sufficiently devoid of contaminants to be used as supply water for dialysis systems.